1. Field of the Invention
The present invention relates to a valve device, and more particularly to a relief-valve device for an air pressure gauge; the relief-valve device can be further fabricated into an air pressure gauge for measuring internal pressure of an inflatable product, and is able to finely deflate the inflatable product for reducing excessive internal pressure thereof.
2. Description of Related Art
Conventional air pressure gauges are used for detecting and ensuring internal pressure in inflatable products such as basketballs and tires at a predetermined value. A conventional air pressure gauge has a relief valve for deflating the inflatable product for reducing the over high internal pressure thereof. However, the relief valve on the air pressure gauge always operates at a deflating speed too fast to finely and precisely adjust the internal pressure so that the inflatable product is usually over-deflated by the relief valve and a user needs to re-inflate the inflatable product for acquiring a precise internal pressure.
To overcome the shortcomings, the present invention provides a relief-valve device for an air pressure gauge to mitigate or obviate the aforementioned problems.